In the crushing operation, which occurs in the below-ground mining facilities, large chunks of kimberlite are broken up into more easily transportable segments. After an initial crushing, the kimberlite passes through a grizzly, or a set of iron bars. If the crushed chunks do not pass through the grizzly, they are still too large, and they are sent back for further crushing. The crushed kimberlite is then taken above the surface for further processing. When no more kimberlite is found entering the cones, the area is depleted and work moves on to a lower level.